The present invention relates to automotive seat recliners and, more particularly, to a manual clutch release seat recliner having a gearing mechanism to permit the controlled reclining of an automotive seat back.
Automotive seats usually comprise a seat bottom that is affixed to a seat frame. The seat frame is mounted to the floor of the vehicle and is usually of a rail type design to allow the forward and rearward adjustment of the seat bottom. The seat back is attached to the seat bottom by a seat back support. If the seat is a reclining type seat where the seat back is rotationally movable with respect to the seat bottom, a locking and release mechanism must be provided. The seat reclining mechanism usually comprises a base that is affixed to the structure of the seat bottom. The seat back support is pivotally mounted to such base as it is desirable to have the seat back move forward and rearward with the seat bottom. The locking and release mechanism by which the seat back is held in a fixed angular relative to the seat bottom has several known forms. One form is a ratchet mechanism wherein a notched wheel is affixed to either the seat back or seat bottom and a pawl is attached to the other. Upon the pawl disengaging the notched wheel, the seat back is released and is free to rotate at is pivot with respect to the seat bottom. Other types of engaging or intermeshing gear type mechanisms all provide a locking and a releasing operation between the seat bottom and seat back.
Certain drawbacks are present in these known seat back locking and release mechanisms. Due to the potentially great forces to which a vehicle seat back can be subjected, a locking mechanism at the pivot between the seat back and the seat bottom must be a relatively sturdy and heavy unit. This is undesirable in the ongoing attempt at decreasing the weight of vehicles to achieve greater fuel efficiency. Another problem with such known locking and release mechanisms concerns the abrupt release and locking of the mechanism. If a passenger desires to rotate the seat back with respect to the seat bottom, and the locking mechanism is a ratchet and pawl assembly, once the pawl is released there is no restraint on the seat back. There is no clutching possible in such an arrangement wherein the seat restraining force could gradually be released to allow the passenger to move the seat as desired and then reengage the locking mechanism. Such known mechanisms are either locked or released with no partial "in-between" settings possible. Such a clutching or partial release operation of a locking mechanism is desirable.
A final problem with such known seat back support locking mechanisms is that a finite number of reclined positions are possible depending on the number of notches in the ratchet wheel. Because of the strength required of the locking mechanism, it is not desirable to make the notches very small and closely spaced to provide many possible reclining positions. Rather, the number of reclining positions is rather limited because of the need to have quite strong notches and protrusions from the ratchet wheel. A locking mechanism having an infinite number of settings is desirable.
Accordingly, it is an object of the present invention to provide an improved reclining seat back locking mechanism. SUMMARY OF THE INVENTION
The present invention provides a seat recliner mechanism having a seat back support pivotally mounted to a base frame associated with the seat bottom. A latch and clutch release mechanism provides controlled reclining of the seat back.
A structural position of the seat back is affixed to a seat back support. Such seat back support is an elongated metal piece which may have flanged edges for additional strength. The seat back support is joined at a pivot pin which extends through a hole near the lower end of the seat back support. The pivot pin is mounted between an elongated outer plate and an elongated inner plate which are held in spaced relation to each other by spacer elements such as rivets and which together form a base frame. This base frame is mounted to a structural portion of the seat bottom. The base frame and the seat back support are usually located on the outer edge of the seat assembly. This permits the seat frame and seat back support to be accessible for adjustment or repair by the simple removal of a cover plate.
A sector gear is affixed to the lower position of the seat back support usually by welding. The sector gear typically comprises a wedge shaped sector of a circular toothed wheel, having a hole at about the center curvature of its curved edge. The curved edge includes teeth forming the gear. The sector gear also includes a stop pin extending from the flat surface of the sector gear about half-way between the hole and the toothed edge. The hole receives the pivot pin which provides the pivot between the seat back support and the base frame. The stop pin extends through a curved opening in the outer plate of the base frame. The rotational movement of the seat back is thusly limited to the length of the curved opening.
A first gear set comprises a smaller diameter toothed wheel or gear and a larger diameter toothed wheel or gear having their center axis openings aligned such that the wheels are mounted on the same shaft. Both wheels rotate with the shaft. This shaft comprises a support pin having ends that extend into openings in the outer and inner plates of the base frame. The smaller toothed wheel is in meshed engagement with the toothed edge of the sector gear. A coiled assist spring is frequently placed around the one end of the pin that extends out from the outer plate of the base frame. The end of the spring extending out from the coil is engaged with the outer plate. The surface of the pin to which the spring is mounted is in contact with the smaller toothed wheel. Accordingly, the spring assists in bringing the seat back upward from a reclined position by aiding the rotation of the smaller toothed wheel and, in turn, the sector gear which is affixed to the seat back support.
A second gear set comprises a smaller diameter toothed wheel or gear and a larger diameter toothed wheel or gear having their center axis openings aligned such that the wheels are mounted on the same shaft. Both wheels rotate with the shaft. This shaft comprises a support pin having ends that extend into openings in the outer and inner plates of the base frame. The smaller toothed wheel is in meshed engagement with the larger toothed wheel of the first gear set. A clutch spool has a center axis opening receiving a support pin having ends that extend into openings in the outer and inner plates of the base frame. The clutch spool has a toothed wheel or gear that is meshed with the larger toothed wheel of the second gear set. The clutch spool rotates on the shaft with the toothed wheel. Two coil springs are coiled around the clutch spool. The springs are wound in opposite directions and are placed in tandem on the clutch spool. One end of the each of the springs extends outwardly therefrom and such ends laterally adjacent each other with a vertical space therebetween. The tension of these springs keeps the clutch spool from rotating and, accordingly, acting through the various meshed gears, keeps the seat back support locked from rotation. The use of two oppositely wound springs is preferred as this provides positive tension in both directions of rotation of the clutch spool. But one spring of appropriate tension could also be utilized.
A clutch release plate is mounted on support pins set in the outer plate of the base frame. The clutch release plate is an elongated metal piece having slots receiving the support pins such that the plate is slidable. An end section of the clutch release plate extends into the vertical space between the springs on the clutch spool. If only one spring were used, the end section of the release plate would be affixed with it. A clutch release lever has an opening that receives one of the clutch release plate support pins such that the release lever is rotatable about such pin. A handle usually extends from the release lever. An end section of the release lever extends into an opening in the clutch release plate or engages the release plate in another manner such that upon the rotation of the release lever, the clutch release plate is slid forwardly along its slots. This sliding action causes the end section of the release plate to separate the coil springs around the clutch spool and thereby lessen the tension in the clutch spool an amount proportional to the degree that the release lever is rotated. When the release lever is released, a separate return spring acting on the release plate pulls the release plate backwardly and causes the full spring tension to be returned to the clutch spool, thereby locking the seat back in the desired reclined position.
It is seen that the seat recliner mechanism of the present invention overcomes the problems of the known systems. The clutch of the present invention need not be overly large or weighty as the gear mechanism provides about a twenty to one mechanical advantage in reducing the seat back load seen by the clutch spool. The clutch may be partially released to allow small adjustments in the degree of seat back reclining, or may be totally released to allow large rapid adjustment in the seat back. Finally, the spool type clutch provides locking of the seat back in an infinite number of desired degrees of reclining.
It should be understood that the use of two gear sets with the sector gear and the clutch spool is a preferred embodiment of the present invention. It would be a matter of design choice to use only one gear set or three or more gear sets. The important feature is that the seat back loading is reduced such that the wrap spring clutch can provide the necessary locking forces. Such locking forces are regulated to certain minimums by industry standards.
In particular, the present invention provides a seat recliner comprising a seat back support, a sector gear affixed to said seat back support, a base frame including an iner plate and an outer plate held in spaced relationship by spacer elements, a pivot means joining said seat back support and said sector gear to said base frame, a first gear set mounted on a pin set between said inner plate and said outer plate of said base frame, said first gear set having a first toothed gear meshed with the teeth on said sector gear and a second toothed gear, a clutch spool mounted on a pin set between said inner plate and said outer plate of said base frame, said clutch spool having a toothed gear meshed with the second toothed gear of said gear set, a spring coil means around said clutch spool such that when tensioned, said spring coil means prevents said clutch spool from rotating and thusly locks said back support in a selected position, and a clutch release plate mounted on said base frame, said clutch release plate affixed to said spring coil means in a manner such that upon a selected movement of said clutch release plate, the tension of said spring coil is released to prevent rotation of said clutch spool thereby permitting the rotational movement of said seat back support at said pivot means.